A166885 Column 1 of triangle A166884.

1, 1, 3, 15, 114, 1159, 14838, 229401, 4159662, 86580636, 2034850425, 53303009286, 1539990513588, 48648616439496, 1668228105283302, 61715049142446537, 2450018515737072792, 103892256368706869356, 4686744256645813560957

Offset: 1

Author

Paul D. Hanna, Nov 21 2009

Keywords

• nonn

Comments

Triangle A166884 transforms diagonals in the triangle A166880 of coefficients in the successive iterations of x+x^2+x^3.

Crossrefs

Cf. A166880, A166884, A166886, A166887.

Programs

PARI

{a(n)=local(F=x, M, N, P, m=n); M=matrix(m+2, m+2, r, c, F=x; for(i=1, r+c-2, F=subst(F, x, x+x^2+x^3+x*O(x^(m+2)))); polcoeff(F, c)); N=matrix(m+1, m+1, r, c, M[r, c]); P=matrix(m+1, m+1, r, c, M[r+1, c]); (P~*N~^-1)[n+1, 1]}